1. Field of the Invention
This invention relates generally to an activated carbon for odor control and method for making same, and more particularly, to an activated carbon-metal oxide matrix to control odor in a gaseous stream, and method of making same.
2. Description of the Related Art
Activated carbons have long been known for their capacity to sorb odors. Activated carbons capture substances generally through physical sorption, chemical sorption and catalytic reaction. It is well known that the presence of metals in activated carbon can enhance the efficiency and selectivity of the activated carbon in sorptive or filtering applications. Methods for producing porous structural materials containing adsorbent particles of activated carbon and metals or metal oxides are conventionally known.
Activated carbon impregnated with metals are typically formed by dispersing activated carbon powders in a solution of a metal salt. The powder is filtered out, dried, and heated to decompose the salt to the desired metal or metal oxide catalyst. Multiple impregnations are usually required to obtain the desired quantity of catalyst on the activated carbon.
Another technique for making activated carbon supported catalysts involves depositing a catalyst metal precursor with high vapor pressure onto a carbon surface. Other methods are known to include extruding activated carbon particles with metal or metal oxide particles and a binder.
Siren, in U.S. Pat. No. 4,242,226, discloses an activated carbon matrix filter material having a metal uniformly dispersed therein. The matrix is obtained by chemically reacting cations that comprise the metal with anion groups chemically bound to a polyhexose derivative. The reaction product is separated, pyrolysed and activated.
Tachibana, in U.S. Pat. No. 4,970,189, discloses fine metal particles dispersed in a carbonaceous mixture. The carbonaceous mixture may be obtained by mixing metal oxide particles with an organic substance and carbonizing the mixture in a non-oxidizing atmosphere to convert the organic substance into a porous carbonaceous body and to convert the metal oxide particles into elemental metal particles dispersed in the carbonaceous body. The metal oxide particles may be coated with an anionic surfactant to provide homogeneity in dispersion of the metal oxide in the organic substance.
Gadkaree et al., in U.S. Pat. No. 5,488,023, disclose a method for making an activated carbon supported catalyst comprising combining a carbon precursor and a catalyst precursor, curing the carbon precursor if necessary, carbonizing the carbon precursor, and activating the carbon. The activated carbon supported catalyst can take the form of a coating on a substrate, a powder, or a monolithic body.
Other examples of activated carbons and metal oxides include: U.S. Pat. No. 4,482,641 to Wennerberg; U.S. Pat. No. 4,31,003 to Lang et al.; U.S. Pat. No. 5,948,398 to Hanamoto et al., and U.S. Pat. No. 5,997,829 to Sekine et al.